A low cost stereophotogrammetric system for the evaluation of tridimensional head translations during visual tasks.

A simple, low cost and easy-to-operate 3D stereophotogrammetry system was developed to measure the kinematic pattern of head stabilisation during visual tasks. The system differs from commercially available ones since it: (a) takes into account the gaze motor coordination characteristics and measures the head translations quantified at the point that best represents the translations caused by the eyes' movement during visual tasks, that is, the midpoint between the eyes; (b) offers minimum restriction to the head movement and minimum interference with it; (c) innovates when using the position coordinates produced by a free-online tracker software. The system was effective in recording the head movements and its RMS total error was 0.